Insulating fabric.



C. E. SKINNER.

INSULATING FABRIC.

APPLICATION FILED MAY Is. 1910.

1,161,989'l Patented Nov. 30, 1915.

wIINEssEs: INVENTOR l 4 l l f ATTORNEY UNITED STATES PATENT OFFICE.

CHARLES E. SKINNER, OF WILKINSBURG, PENNSYLVANIA, ASSIGNOR T0 WESTING-HOUSE ELEC-TRIO AND MANUFACTURING COMPANY, A CORPORATION OF PENNSYL-VANIA.

INSULATINC- FABRIC.

Specication of Letters Patent.

Patented Nov. 30, 1915.

Original application iled October 7, 1908, Serial No. 456,609. lDividedand this application led May 16, 1908. .Serial No. 561,746.

To all ywhom t may concern.'

Be it known that I, CHARLESE. 'SKINNER, a citizen of the United States,and a resident of Wilkinsburg, in the county of Allegheny and State ofPennsylvania, have invented a new and useful Improvement in InsulatingFabrics, of which the following is a specification, this applicationbeing a division of m application, Serial No. 456,609, filed Octo er1908. l

My invention relates to insulating fabrics for electrical apparatus andit has for its object to provide a fire-proof fabric which shall beadapted for use at relatively high temperature.

Field coils for dynamo-electric machines have heretofore beenconstructed by winding copper stra or ribbon into a rectangular helix,and, since the voltage between turns in coils of this character isrelatively low, strips of insulating material have usually been insertedbetween the turns of the helix in pref- -erence to Wrapping theconductor with insulating tape or completely covering it by other means,in order to improve the ventilation of the winding.

According to my present invention, I provide a fabric composed of metalfoil or very thin metal ribbon which hasV been so treated as to producea hard film or coating of insulation on its surface. Since foil ofapproximately one-thousandth of an inch in thickness may be employed,the space occupied by the insulation is relatively small while, at thesame time, the coil, or other electrical conductor with which it isused, is rendered fire-proof and capable of operation at hightemperatures. The coated metal foil (preferably aluminum) may be used incombination with sheet mica, the foil serving to hold the mica sheets orflakes in position, thereby avoiding the necessity for paper or othercarbonizable fabric, such as is usually employed.

Figure 1 of the accompanying drawings, is a sectional view, on a largescale, of a sheet or strip of metal foil which has been treated toproduce the insulating fabric of my invention. Fig. 2 is a similar Viewof an insulating fabric which is built up of several layers of the kindshown in Fig. 1 and separated by sheet mica or other similar insulatingmaterial. Fig.- 3 is a perspective view of an insulating ribbon or stripwhich is similar in construction to the fabric of Fig.

shown in section, 1s composed of three layers 4, 5 and 6 of coatedaluminum foil separated by layers 7 and 8 of mica or other similarinsulating material. By using the mica flakes, in combination with thealuminum foil, the insulating fabric is adapted to insulate forrelatively high voltages While, at the same time, no combustiblematerial is introduced.

I prefer to emplo" strips of aluminum foil of substantiallyone-thousandth of an inch in thickness in order that a minimum amount ofspace ,may be occupied by the insulation when used in connection Withcoils and other current-conducting parts.

An especially good insulating film may be obtained by passing the stripof aluminum through a bath of ammonium borate, or some other suitableliquid, and, at the same time, passing electric current through theconductor and the bath. By this means, an aluminum oxid film, which isrelatively hard and is not readily destroyed by heat, is produced.Either one or both of the surfaces of the metal foil may be covered withthe insulating film.

My invention is not limited to use with any particular form or type ofelectric apparatus but is capable of application for all insulatingpurposes where sheet insulating material c'an be employed.

I claim as my invention:

1. A fire-proof material for insulating electric conductors consistingof metal foil having a heat-resisting coating of hard insulatingmaterial upon its surface.

2. A fire-proof material for insulating electric conductors consistingof aluminum foil having a heat-resisting coating of hard insulatingmaterial formed upon its surface.

3. A lire-proof insulation comprising alternate layers of metal foilhaving insulating coatings on their surfaces and other heatresistinginsulating material.

4. A fire-proof insulating material comhaving oxid insulating coatingson their surfaces and mica flakes, the mica flakes held being inposition by the foil.

In testimony whereof, I have hereunto subscribed my name this 3rd' dayof May,

5. A fireproof insulating material com- 1910. v prising non-combustiblesheet material coated CHARLES E. SKINNER. with non-combustibleinsulating material. Witnesses:

A ireproof insulating material comprising oxidized aluminum fm1.

F. E. OLIVER, B. B. HINES.

It is hereby certified that in Letters Patent No. 1,161,989, grantedNovember 30,

1915, upon the application of Charles E. Skinner, of Wilkinsburg,Pennsylvania,

for an improvement in Insulating Fabrics, errors appear in the printedspecification requiring correction as follows: Page 1, line 15, for theword temperature read temperatures; page 2, lines 1-2, for the Wordsheld being read beingbeld; and

that the said Lettersl Patent should be read with these correctionstherein that the same may conform to the record of the case in thePatent Ofce.

Signed and sealed this 18th day of January, A. D., 1916.

[SEAL] J'. T. NEWTON,

Acting Commissioner Q7" Patents. Cl. 173-320.

